To quickly establish a radio network at low costs when there is no equipment room or an equipment room is not at an ideal location, a distributed base station solution is proposed. In this solution, a Radio Remote Unit (RRU) and a baseband control unit (BBU) are separated from each other by using a radio remote distribution technology, and are connected by using a fiber or a cable. Digitally sampled and quantized In-phase/Quadrature (I/Q) data is transmitted between the BBU and the RRU by using a Common Public Radio Interface (CPRI).
An Optical transport network (OTN) may be used as a bearer network between the BBU and the RRU. To enhance network reliability, the OTN generally performs service protection by using an active fiber and a standby fiber. As shown in FIG. 1, after being converged to an OTN device A, services of multiple RRUs are transmitted to an OTN device B by using a working trail. The OTN device B sends the received services to the BBU. If the working trail between the OTN device A and the OTN device B is faulty, the services may be switched to be transmitted by using a protection trail.
FIG. 2 is a schematic diagram of a fault detection manner of an OTN device in the prior art. As shown in FIG. 2, the OTN device detects a fault by using an optical module and an OTU overhead detection module, generates alarm information, and reports the alarm information to a protection switching control module. After receiving the alarm information, the protection switching control module switches a service from a working trail to a protection trail. It takes a relatively long time, which is generally at a millisecond level, from the moment when the working trail is faulty to the moment when the OTN device detects the fault and reports the alarm information. Consequently, protection switching efficiency is low.